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Microchip Technology 25LC640AT-E/SN
- Part No.:
- 25LC640AT-E/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
25LC640AT-E/SN.pdf
- Description:
- IC EEPROM 64KBIT SPI 10MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,632
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Product details
Overview
25LC640AT-E/SN from Microchip Technology Inc. is a 64-Kbit SPI Serial EEPROM with 8192 × 8-bit organization, 32-byte page size, and industrial temperature range (–40°C to +85°C). It operates at up to 10 MHz clock frequency with 5 mA read/write current at 5.5 V and supports hardware write protection via WP pin and STATUS register. It is used in microcontroller-based systems for nonvolatile parameter storage, calibration data retention, and firmware configuration.
For engineers reviewing the 25LC640AT-E/SN datasheet, 25LC640AT-E/SN pinout, 25LC640AT-E/SN application, or 25LC640AT-E/SN equivalent, key selection criteria include SPI timing compliance at 1.8–5.5 V, page-write boundary handling, HOLD functionality for interrupt-safe communication, and AEC-Q100-qualified variants for automotive subsystems.
Technical Context
The 25LC640AT-E/SN implements a standard SPI Mode 0,0/Master-Slave interface with separate SI (data-in) and SO (data-out) lines, requiring CS, SCK, and optional HOLD/WP control. Its internal architecture includes a 32-byte page latch, EEPROM array with high-reliability floating-gate cells, and status register with WIP, WEL, BP0/BP1, and WPEN bits.
Write operations require explicit WREN instruction before WRITE or WRSR, followed by CS high to initiate self-timed internal write cycle (≤5 ms). The HOLD pin suspends ongoing SPI transfers without resetting address pointers, enabling deterministic host interrupt servicing while preserving transaction state.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit), sufficient for storing bootloader parameters, sensor calibration tables, or device identity data in space-constrained designs. |
| Interface | SPI-compatible serial bus (Mode 0,0), compatible with PIC® and other MCU SPI peripherals without bit-banging overhead. |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5 V; reduces to 5 MHz at 2.5–4.5 V and 3 MHz at 1.8–2.5 V - enables bandwidth scaling with supply voltage. |
| Page Size | 32 bytes - defines maximum contiguous write length per CS assertion; crossing physical page boundaries causes wraparound, requiring software boundary checks. |
| Endurance & Retention | 1,000,000 erase/write cycles and >200 years data retention - validated for long-life industrial logging and infrequently updated configuration storage. |
| Supply Voltage Range | 2.5 V to 5.5 V - supports direct interfacing with 3.3 V and 5 V logic domains without level shifters. |
| Operating Temperature | –40°C to +85°C (Industrial grade) - qualified for use in factory automation controllers, power supplies, and embedded gateways. |
Pinout & Package
25LC640AT-E/SN is packaged in an 8-lead narrow SOIC (SN) with 150-mil body width and standard 0.050" lead pitch. Pin 1 is marked with a beveled corner or dot; package meets JEDEC MS-012AA and RoHS requirements.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 1) | Chip Select Input | Active-low enable signal; must be low for all SPI transactions; rising edge after valid write initiates internal write cycle. |
| SO (Pin 2) | Serial Data Output | Tri-state output delivering memory contents on falling SCK edge; enters high-Z when CS is high or HOLD is asserted. |
| WP (Pin 3) | Hardware Write-Protect Input | Low-active pin that, when enabled via WPEN bit, blocks writes to STATUS register nonvolatile bits - prevents accidental lockout of memory regions. |
| VSS (Pin 4) | Ground Reference | Primary return path for all internal circuitry and I/O drivers; must be connected to system ground plane with low impedance. |
| SI (Pin 5) | Serial Data Input | Latches instructions, addresses, and data on rising SCK edge; accepts 8-bit opcodes (e.g., 0x03 for READ, 0x02 for WRITE). |
| SCK (Pin 6) | Serial Clock Input | Synchronizes all data transfers; rising edge clocks SI, falling edge updates SO; max frequency depends on VCC. |
| HOLD (Pin 7) | Transaction Pause Control | Low-active input that freezes SPI state machine without resetting address pointer - allows host to service higher-priority interrupts mid-transfer. |
| VCC (Pin 8) | Power Supply | 2.5–5.5 V supply; internal regulation ensures stable core voltage across operating range; decoupling capacitor required near pin. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed write cycle | ≤5 ms internal erase/write completion - eliminates need for external timeout polling; WIP bit in STATUS register indicates busy state. |
| Block write protection | Configurable via BP0/BP1 bits to protect none, upper 1/4 (1800h–1FFFh), upper 1/2 (1000h–1FFFh), or full array (0000h–1FFFh) - enables secure boot partitioning. |
| Power-on data protection | Write enable latch resets at power-up, and WRDI instruction clears it - prevents spurious writes during brown-out or reset conditions. |
| HOLD pin functionality | Pauses active SPI sequence without losing address pointer or command state - enables deterministic real-time interrupt response in safety-critical firmware. |
| ESD robustness | ≥4 kV HBM ESD rating on all pins - enhances reliability in manufacturing, field service, and electrostatic-prone industrial environments. |
Applications
| Industrial PLC Configuration Storage | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: Storing I/O mapping tables, PID tuning parameters, and fault log history in programmable logic controllers deployed in factory floors. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via SPI during boot and runtime reconfiguration; HOLD pin used during motion-control interrupt servicing. Use Value: Ensures deterministic parameter persistence across 1M+ power cycles and >200-year data retention, eliminating battery-backed SRAM maintenance. | Use Scenario: Holding seat position presets, mirror angle offsets, and lighting profiles in automotive BCMs operating across –40°C to +85°C ambient. IC Role / Device Role / Timing Role: SPI EEPROM interfaced to 32-bit ARM Cortex-M MCU; WP pin tied low with WPEN set to prevent accidental overwrites during CAN firmware updates. Use Value: AEC-Q100 qualification and 1M endurance support 15+ year vehicle lifecycle with zero field failures due to memory corruption. |
| Medical Infusion Pump Calibration Data | Smart Energy Meter Firmware Settings |
Use Scenario: Storing flow-rate calibration coefficients, motor step compensation values, and usage audit logs in Class II medical devices requiring traceable parameter history. IC Role / Device Role / Timing Role: Secure nonvolatile storage accessed only during calibration mode; STATUS register write-protection prevents tampering with BP bits post-certification. Use Value: >200-year data retention and 4 kV ESD immunity ensure regulatory compliance and long-term accuracy without recalibration drift. | Use Scenario: Maintaining tariff schedules, meter ID, CT ratio settings, and firmware update flags in ANSI C12.20-compliant smart meters deployed in outdoor substations. IC Role / Device Role / Timing Role: SPI EEPROM sharing bus with RTC and metrology ADC; HOLD pin used during time-critical energy pulse counting to avoid SPI contention. Use Value: Industrial temperature range and 2.5–5.5 V operation allow direct connection to 3.3 V meter SoC without voltage translation, reducing BOM cost and board area. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA640AT-I/SN | Wider VCC range (1.8–5.5 V); identical pinout, timing, and memory map; same SOIC-8 package. | Supports 1.8 V logic domains (e.g., ultra-low-power MCUs); not AEC-Q100 qualified. | Select when interfacing with 1.8 V systems or requiring extended low-voltage operation below 2.5 V. |
| AT25DF641A-SHN-T | Dual/quad SPI interface; 64 Mbit density; different command set and status register layout; requires firmware adaptation. | Higher density and faster quad-read modes; intended for code shadowing or firmware storage, not parameter EEPROM replacement. | Select only if migrating to flash-based architecture with dual/quad SPI host support and need >64 Kbit capacity. |
Compared with 25AA640AT-I/SN, the 25LC640AT-E/SN offers tighter VCC min (2.5 V vs. 1.8 V) but adds AEC-Q100 qualification; compared with AT25DF641A-SHN-T, it provides simpler SPI protocol, lower power, and guaranteed byte/page write atomicity - critical for configuration integrity.
Availability
25LC640AT-E/SN is available at Aetrix Electronics and suitable for industrial automation, automotive electronics, and medical device applications requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.
Supply support for 25LC640AT-E/SN includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Microchip Technology Inc. is a leading provider of microcontrollers, analog components, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25LC640A product line delivers SPI serial EEPROMs optimized for reliable, low-power, and pin-efficient nonvolatile storage in resource-constrained embedded systems across industrial, automotive, and consumer markets.
FAQ
What is the maximum clock frequency supported by the 25LC640AT-E/SN across its full voltage range?
The 25LC640AT-E/SN supports up to 10 MHz at VCC ≥ 4.5 V, 5 MHz at 2.5 V ≤ VCC < 4.5 V, and 3 MHz at 1.8 V ≤ VCC < 2.5 V. Since the 25LC640AT-E/SN has a minimum VCC of 2.5 V, its operational clock range is 5–10 MHz depending on supply voltage. This stepped frequency scaling ensures timing margin across voltage variations without requiring dynamic clock adjustment in host firmware.
Does the 25LC640AT-E/SN require external pull-up resistors on its SI, SO, or HOLD pins?
No, the 25LC640AT-E/SN does not require external pull-ups on SI, SO, or HOLD. SI and HOLD have internal weak pull-ups; SO is actively driven or tri-stated and relies on host-side termination when shared on multi-drop buses. External pull-ups may be added for noise immunity in high-EMI environments, but they are not mandatory per the 25LC640AT-E/SN datasheet specifications.
How does the HOLD function behave if asserted while SCK is high?
If HOLD is pulled low while SCK is high, the 25LC640AT-E/SN will not enter HOLD mode until the next SCK high-to-low transition. To ensure deterministic pause behavior, HOLD must be asserted only when SCK is low. Once paused, SI, SCK, and SO enter high-impedance states and ignore transitions until HOLD is raised while SCK remains low - this precise timing requirement is defined in the 25LC640AT-E/SN functional specification.
Can the 25LC640AT-E/SN be used in automotive applications requiring AEC-Q100 qualification?
Yes, the 25LC640AT-E/SN is explicitly AEC-Q100 qualified for automotive applications. The "E" in the part number denotes Extended temperature range (–40°C to +125°C), and Microchip's official documentation confirms AEC-Q100 qualification for the 25LC640A family. This makes the 25LC640AT-E/SN suitable for body electronics, infotainment backup storage, and ADAS subsystem configuration memory where automotive-grade reliability is mandated.
What happens if a page write crosses a 32-byte boundary on the 25LC640AT-E/SN?
If a page write command attempts to cross a 32-byte physical page boundary on the 25LC640AT-E/SN, data wraps around to the start of the same page instead of advancing to the next page. For example, writing 32 bytes starting at address 0x1FF0 wraps bytes 0x1FF0–0x1FFF into 0x1FF0–0x1FFF and then overwrites 0x1F00–0x1F0F. This behavior is documented in the 25LC640AT-E/SN datasheet and requires application firmware to enforce page-aligned writes or split multi-page transfers.
25LC640AT-E/SN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 64Kbit
- Memory Organization:
- 8K x 8
- Memory Interface:
- SPI
- Clock Frequency:
- 10 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 2.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
25LC640AT-E/SN FAQ
1.How can I place an order for 25LC640AT-E/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC640AT-E/SN on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for 25LC640AT-E/SN reliable?
The price and inventory of 25LC640AT-E/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25LC640AT-E/SN is usually 5 days.
3.What payment methods are accepted for 25LC640AT-E/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC640AT-E/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC640AT-E/SN?
25LC640AT-E/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC640AT-E/SN order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for 25LC640AT-E/SN?
For technical support, including 25LC640AT-E/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC640AT-E/SN requirements.
6.How does Aetrix verify that 25LC640AT-E/SN is sourced from the original manufacturer or authorized distributors?
All 25LC640AT-E/SN products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 25LC640AT-E/SN meets industry standards.
7.What is the process for return or replacement of 25LC640AT-E/SN?
All 25LC640AT-E/SN units undergo pre-shipment inspection (PSI). If there is an issue with 25LC640AT-E/SN, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The 25LC640AT-E/SN part is unused and in its original packaging.
Return procedure for 25LC640AT-E/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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